1. Field of the Invention
The present invention relates to a nonvolatile semiconductor memory device for nonvolatilely writing data in accordance with application of a voltage to a variable resistive element.
2. Description of the Related Art
As a technology for realizing the microstructure of a memory cell, a resistance variation type memory employing a variable resistive element for the memory cell has been proposed. The variable resistive elements including a phase change memory element that changes the resistance value due to a change in the crystalline or amorphous state of a chalcogenide compound, an MRAM element employing a resistance change due to a tunneling magneto-resistance effect, a memory element of a polymer ferroelectric RAM (PFRAM) in which a resistive element is formed of conducting polymer, and an ReRAM element causing a resistance change by application of an electric pulse are well known (patent document 1: JP-A-2006-344349).
This resistance variation type memory can compose the memory cell of a series circuit of a Schottky diode and a variable resistive element, instead of a transistor, and has an advantage of achieving higher levels of integration with a three dimensional structure because of easy lamination (patent document 2: JP-A-2005-522045).
In the case where the resistance variation type memory is used, it is required to boost the voltage of one wirings (word lines or bit lines) connected to the unselected memory cells, or one wirings connected to all (unselected and selected) memory cells, so that a reverse bias may be applied to the memory cell, before all the operations. With this operation, a parasitic capacitance of the memory cell is charged to generate a charging current.
However, the charging current to the parasitic capacitance is larger as the resistance variation type memory is integrated at higher level. Thereby, a power noise occurs, possibly causing a malfunction.